1. Field of Invention
Embodiments of the invention, in general, relate to power measurement on circuit boards and more specifically, the embodiments of the invention relate to isolated current and voltage monitoring.
2. Description of the Background Art
Printed Circuit Boards (PCBs), line cards and electronic assemblies (hereinafter referred to as boards) typically have a power-input section and a digital-circuit section. The power-input section accepts power at a primary DC input voltage termed as a primary potential. The digital-circuit section operates on a relatively small DC voltage termed as a secondary potential. Sections of a board functioning at the primary potential are collectively termed as a primary side. Similarly, various sections functioning at the secondary potential are collectively termed as a secondary side.
The input current is continuously measured and monitored, to prevent any damage or interruption in the digital circuit section on the board. Monitoring can be done in the power input section that controls the switching on or off of the power input and inrush current. For example, monitoring can be performed at an active fuse section, or a hot-swap section. The active fuse section includes an inrush limit Integrated Circuit (IC) or an active fuse IC. The active fuse section is at the primary potential. However, all environment-monitoring functions are referenced to the secondary potential. The environment-monitoring functions include current monitoring, voltage monitoring, temperature monitoring, and so forth.
Safety-approved isolation circuits are used for the transfer of current and voltage from the primary side to the secondary side. Isolation amplifiers can be used for such transfers, but they are relatively expensive and complex. Current shunts, or shunt resistors, used with the isolation amplifiers dissipate heat, leading to inefficiency of the isolation circuit.